Copper cabling transmits data by varying or switching electrical current through a conductor, and remains a foundational medium in network infrastructure due to its low cost and ease of installation. This content covers how copper works, its key advantages and limitations, and the techniques used to mitigate signal degradation and interference.
Copper Data Transmission
Copper is a conductor of electricity, which means that there are a bunch of electrons all up and down a copper wire. What's happening is that when we apply power to a copper wire, we are either moving the electrons in one direction, in the case of direct current, or we're moving these electrons back and forth, in the case of alternating current. So when we're talking about electricity through a cable, all we're talking about is these electrons moving through this cable.
We can transfer or transmit data by turning the power on and off to this, or by having varying degrees of power. So we can send a signal from one location to the next by either turning the electrons on and off or varying the degree in which these electrons are flowing through this cable.
To make a copper cable is relatively cheap in comparison to something like fiber optics. Copper is a cheaper metal, although it's definitely more expensive than some metals. But it's definitely less expensive than making a fiber optics cable.
It is much more reliable than wireless. Wireless tends to be a little finicky, so copper tends to be a very stable connector that's out there.
It's also relatively easy to install. With fiber, if you bend it too much then it can crack. Copper you can bend around, you can pull it through different locations, and there are some shielding and stuff that can go around it to protect it. So it tends to be a really easy cable to pull through your ceilings and pull through walls and pull through crawl spaces.
Unfortunately, there are some disadvantages to copper. As we run these cables, the longer they get, the more resistance they put up, and it degrades the signal. This is what we call attenuation. So over distance, there's only certain lengths that these cables can go before the signal is unreadable on the other side. That's one disadvantage: the distance of copper is less than what fiber would be.
Another thing is that these lines are susceptible to EMI, or electromagnetic interference. When electrons run through a cable, it lets off these fields. An electron, as it goes through this cable, there's these fields that it emits. Now, different cables can interfere with other cables. So for instance, let's say a power line runs across this, or even worse, next to it. The electrons running through that power cable can create these fields that will then interrupt the electrons within our data communication.
Another example is that a lot of times we'll run cables next to each other, or even within the cable there's multiple pairs within each of these cables running next to each other, and so those lines will interfere with each other with this electromagnetic interference. We call that cross talk. So when one line is, you'll get bleed over into the next line, and that's what we call cross talk. So that is also a disadvantage of copper lines.
There are ways that we can overcome some of these disadvantages. For instance, attenuation comes in when we go too far of a distance with these cables. To combat attenuation, we just make limits on how far we can run these lines. For instance, a copper Ethernet connection is only supposed to be ran about 100 m. So 100 meters is about what they figure the limit is. You can certainly go past this level of 100 meters, but what happens is it introduces more chances of attenuation and then the signal will degrade. You'll get retransmits and the line will not be as clean, or maybe the data has to drop, so we don't have as fast of a connection. So 100 meters is the limit with a lot of our Ethernet cables.
Another thing that we could do is we could create a shielding around this cable. If we have a shielding, some sort of conductor that goes around it, and we ground that out, so we put that to ground, then what we can do is we can shield this data, or the electrons that are going through this, from outside interference. So putting shielding around these cables is one way that we can reduce the effects of EMI.
Another thing that we found is we will take these cables and we will twist them together and create a twisted pair. When we twist those pairs together, then we can reduce the amount of cross talk that happens. Just know that that's another method that we can reduce the amount of cross talk on these lines and take away some of those disadvantages that we have with copper cable.
There's a lot of different copper cables that are out there. A couple of the categories that we will be talking about are Ethernet cables and twisted pair. But there's also coaxial. A lot of you probably have some sort of cable that's running into your home that's transferring data, and a lot of times that cable is coaxial cable that's running into those homes.
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